Message-ID: <29357.200101121237@gemini>
From: "James Moritz" <j.r.moritz@herts.ac.uk>
Organization: University of Hertfordshire
To: rsgb_lf_group@blacksheep.org
Date: Fri, 12 Jan 2001 12:41:18 +0000
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Subject: LF: More Rugby info
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Dear LF Group,

The antennas at Rugby and Criggion have had some modification 
over the years - the original designs both used 8 wire "sausages" 
slung between the masts for the top load. Now both have a sort of 
horizontal spider's web filling the whole area between the masts. 
Rugby still has the original 12 guyed masts, which are 820 feet 
according to the paper. Criggion originally had 3 x 600 foot self  
supporting masts; these were all that was available during the war, 
and were not considered enough, so the station was sited adjacent 
to a cliff, and one side of the top load is anchored to the top of the 
cliff. Since then, 3 x 700 foot guyed masts have also been added 
to the antenna. 

Rugby was also used experimentally for early trans-atlantic 
telephone services, using ssb on about 60kHz. For this purpose, 
the main antenna was divided into two sections, the smaller part 
carrying the telephone signal.

Both VLF antennas also have various smaller L and T antennas for 
LF slung lower down the masts. Rugby has a whole forest of what I 
presume are HF antennas, across the road from the VLF/LF site. 
Originally, Criggion had several HF Rhombics too, but these are 
now gone.

As far as phase control goes, the 1926 paper describing Rugby 
mentions that the frequency was derrived from a valve maintained 
tuning fork. This apparently had a tempco of 100ppm/degC, and 
was regarded as a major advance in transmitter frequency 
stability, and neccessary because of the increasing use of the 
spectrum. By the time Criggion was built 18 years later, crystal 
oscillators with 1 in 10e7 stability over a period of months were in 
use.

If you visit either site, it is worth taking a pair of binoculars, since it 
is hard to see much detail from ground level (but be prepared for 
funny looks from the site staff!). I heard that the telegraph poles 
and cables over the road at Criggion are there to support the top 
load when it is lowered for maintenance.

Cheers, Jim Moritz
73 de M0BMU